Their presence, and impact on the program, even prior to Saturday’s 129th edition of The Game, was immeasurable.

“It’s hard to overstate how much they have meant to us,” summed up their coach, a drained Tim Murphy after watching the talented tandem spearhead a 21-point fourth-quarter blitz as the Crimson charged back for a pulsating 34-24 victory over Yale, their sixth straight in the series.

The closing statement from his two seniors was one for the ages.

The spirited second half in front of a sellout crowd of 31,123 at the Stadium featured four lead changes and a 35-point fourth-quarter flurry. Chapple (22-of-32 passing, 209 yards) was clutch, firing a pair of scoring passes, including a 4-yarder to 6-foot-5-inch junior tight end Cameron Brate for a 27-24 lead with 4:44 left.

“Cam told me, ‘If I’m covered, give me a high ball,’ ” said Chapple, who set up the TD with a 61-yard keeper up the middle to the Yale 9.

It was the finishing scramble on a career-best 128-yard rushing performance (on 18 carries) for the 6-2, 195-pound Chapple, who closes out his magnificent career with a 14-3 record as starter and a number of program standards, including season marks for total offense (3,235 yards) and TD passes (24).

Chapple scored the game’s first touchdown, rolling right and eluding linebackers Brian Leffler and Will McHale (team-high 11 tackles) on the edge for an 18-yard sideline scamper to the right pylon, giving Harvard a 13-3 lead in the third quarter.

Scales delivered the knockout punch in a game Murphy dubbed “a heavyweight fight,” taking a pitch off tackle down the right sideline for a 61-yard burst and 34-24 cushion with 1:08 remaining.

It capped a 19-carry, 177-yard effort — the most yards for a Harvard back against Yale since Eion Hu in 1996 — and pushed the 5-10, 195-pound Scales to 1,002 yards for the season. He raised both arms to the heavens, “for all of the thank-you’s that you can’t express on a daily basis,” he said with a wide grin.

“I have never seen Treavor run that fast,” said Chapple with a smirk. “At that moment, I knew that all of our hard work had come to fruition. Just pure elation, for the team, and this group of seniors.”

With Penn’s 35-28 win at Cornell, those seniors will have to settle for an 8-2 record (5-2 Ivy) and a runner-up finish to the Quakers.

Yale (2-8, 1-6) battled hard the entire 60 minutes for first-year coach Tony Reno, who had spent the previous three seasons on the Harvard side directing the secondary and special teams.

“We just didn’t have to make plays, we had to make really big plays to win this game,” said Murphy, adding, “we had nothing left.”

The Bulldogs bounced back from the 13-3 third-quarter deficit to seize the lead at 24-20 on the second of two short TD runs from their bulldozing sophomore transfer, Tyler Varga (22 rushes, 96 yards).

The Elis capitalized on a short field after defensive tackle Nick Daffin reached up to snare an ill-advised toss over the middle from Chapple at the Crimson 29.

Chapple’s previous pass was a 32-yard laser to a diving Andrew Berg (six catches, 70 yards) in the right corner of the end zone to put the Crimson back on top, 20-17.

“It really got us going offensively,” said Chapple. “Getting the the crowd back into the game, that was a real momentum-shifter.”

Yale, decimated by injury at quarterback, started Derek Russell (9 of 10, 73 yards), a senior from Newton South, but finished with junior Henry Furman (13 of 20, 158 yards), a converted wideout who in the third quarter connected on a 46-yard launch down the middle to Cameron Sandquist to the 5. Two plays later, Varga plunged into the end zone.

The Bulldogs made plays all day. Harvard made a few more at the end.

The loss, while disappointing, reinforced what Reno has witnessed from Yale all season.

“These guys have battled through more things this season than anyone could imagine,” he said. “I am not happy with the result, but these guys showed the world what they are, and what Yale football is all about.”